Ammonia and tar recovery process



1. VAN ACKEHEN. AMMONIA AND TAR RECOVERY PROCESS.

APPLICATION FILED AUG2I| 1919.

Patented Apr. 19,1921.

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1 \.J|..A.| |.L .melnNlllol vJOSEPH VAN ACKEREN, lOE PITTSBURGH, PENNSYLVANIAASSIGNOR TO THE KOPPERS COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION 0F PENNSYLVANIA.

AMllllONIA AND TAR RECOVERY PROCESS.

Leraars.

S'pecication of Letterslatent.

Patented Apr.. 19, 192i.

Application led August 21, 1919. Serial No. 318,868.

To ZZ whom it may-concern Be it known that I, JOSEPH VAN AcKEREiv, a citizen of the United States, residing 1n Pittsburg?, in the county of Allegheny and State of ennsylvania, have invented'a new and useful Im rovement in Ammonla and Tar Recovery lowing is a specification.

This invention relates primarily to the recovery of tar andof ammo-nia from ammonia and tar charged gas, and has for one of its objects the eicient production of a clean, dust-free and high-grade tar, and for a further object the recovery of ammonia, from such gas, as high-grade ammonium sulfate, with great economy of heat, or steam, and with simplicity and directness 1n the operation of the apparatus.

The invention is'of particular utility 1n connection with the process for the recovery of tar and ammonia from producer-gas, and from coke-oven gas, resulting in a combined production of high-grade ammonium sulfate derived from the ammonia of both the producer-gas and the coke-oven gas in a unitary operation, as disclosed in my prior Patent No. 1,307,571, dated June 24, 1919. For convenience, the present description will be confined to this particular use of the invention; it will be understood, however, that the invention is capable of other applications, for example it may be applied to one of these gases, or to gas otherwise derived from the carbonization of coal; therefore it is manifest that the invention is by no means limited in scope to the particular application or specific use herein described. The invention may also have such other objects and results as are found to obtain in the processes hereinafter set forth and claimed. Y

In the accompanying drawings:

Figure 1 is a conventional diagram illustrating an embodiment of the invention in a preferred arrangement of apparatus for practising its processes.

Fig. 2 is a key to the symbols employed in the various lines that show the connections between the apparatus indicated in Fig. 1.

Referring to the drawing. there is indicated at 5 a coke-oven battery, from which coke-oven gas-is derived, and which is ired with producer-gas derived from the gasproducer 6. The evolved producerasfrom the gas-producer 6 passes first to t e dustrocesses, of which the folcatcher 7, preferably in the form of a free chamber in which it is cooled preliminarily by means of cold water, sprayed into said dust-catcher 7, as indicated by the water line 49; also in passing through the dustcatcher, the speed of theproducer-gas is reduced somewhat as a result of the expanded volume of the chamber, whereupon the dust particles which pass over with the gas from the producer drop out from the gas and are precipitated in the bottom of the dustcatcher. The producer-gas entering the dust-catcher is still at a very high temperature, about 450 C., and its water saturation point is only about 80 C., and therefore it is still greatly super-heated with respect to its water and tar, and these and its other vaporizable' content are carried as vapor into and through the dust-catcher 7, and said dust-catcher acts only to free the passing gas from dust and other solid impurities in its current, and partially to cool the gas. Y

From the dust-catcher 7, the producer-gas, after having been partially cooled, but still above its water saturation point, passes to the disintegrator 8. ln the disintegrator thegas is further cooled by contact with cold water sprayed into the disinte rator, as indicated by the water line 4:9, t e gas being subjected to a thorough intermixing treatment with .the cooling water in the disintegrator. The water --from the dustcatcher 7 and disintegrator 8 may pass to a circulating pump 57 to which cooling fresh water is added, and, from the latter be returned to the dust-catcher and disintegrator, thereby maintaining a water circulatin system. From the dislntegrator, the pro ucergas issues with its temperature reduced to about 120 C., and, still carrying its water and tar, as vapor, passes to the compartment 13 of an electrical tar'precipitator, in which it Hows in counter-current with the saturated air, the latter being at a temperature 80 C. At a temperature of 120 C. of the gas, the tar 'begins to dro out, and, approaching the Vcharacter o a -finel comminuted mist, as the gas cools, w1l1 e precipitated; the clean tar so precipitated is discharged into the tar and liquor tank 14, from which it flows into the tar tank 11.

The tar-feed producer-gas passes from the compartment 13, through the gas line 15, to

the hot-acid washer tower 16, which it enters at a temperature of about 80 C., at about its saturation point- In the acid tower, the

ammonia is absorbed from the producer-gas and the ammonia-freed producer-gas leaves the acid washer at atemperature of about 80 C. The acid solution in the'acid tower Vis kept hot by the absorption reaction so that there cannot be any diluting of the 'am- Inoniaabsorbing acid solution that is flowing through said acid washer; and, by reasonof the little super-heatk remaining in the gaspractically no water is icked up by the gas in passing through sai acid washer', and hence'there is no precipitation of ammonium sulfate in said acid washer.

Thence, the ammonia-freed gas loyvs through the acid separator 17, in which it is freed of such. acid as it may carry with it, and then flows through the gas line 18 to the first-stage final cooler 19, through which it lows in counter-current with warm water that enters such cooler at about 50 C. ln this cooler, the-gas is cooled `to about 65 C. and to a great extent dehydrated, and thence passes through the gas line 20 to the second-stage nal cooler 21. Through thev second-stagefinal cooler 21, the gas passes in counter-current with cold water and issues finally dehydrated and cooled down to a temperature of about 25 C. The clean, cool, and relatively dry producer-gas is drawn of through the gas line'22 by the exhauster 23,

which forwards the gas to the producer-gas v 40 holder 24 and on, through the producer-gas line 25, to the before-mentioned coke-ovens .5, in which the producer-gas is burned to provide the heat forthe coking of the coal charges in the oven'. Y

The ammonia-charged acidv solution from the aforesaid acid washer 16 is conveyed to the mother-liquor tank 26 which feeds the'` saturater 27. The mother-liquor tank 26 also receives .the drain from the -saturater drain table 28 and centrifugal drier 29; and-4 the surplus acid solution from said mother-I llquor tank is forced backrby the acid pump 30 to the acid washer 16, with the result that there is maintained a 'constant circulation of lhotacid solution, to. which a portion of fresh acid is constantly added from the acid 65 .perature as before-mentioned of'about 50 heat C., from 4the air saturater tower 33, from which water isdrawn by the warm-waterpump 34; the water issuing from said irst' stage final cooler 19, has a temperature of about 80 C., and is forced by the -hot-water pump 35 to the top of the said air saturater towerinto which it is sprayedthere being, as just mentioned, a constant re-circulationv of water through said irst-stage final cooler and said air saturater tower.

The air to be saturated and heated is forced into said air saturatertower by the air fan 36, and enters the tower at a temperature of about 25 C. The air leaves the tower charged with water-vapor at a temperatu're of about 74 C. and is further chargedwith exhaust-steam passing through the steam line 51 from the exhaust of the fan 52 for conveying the waste gases,'befor e the air enters the beforesmentioned compartnient 13 of the electrical precipitator. Exhauststeam in the steam line 51 is at a temperature of about 102 C., and, mixing with the air saturated at a temperaturel of about 74 C., raises the temperature of the 5 air, withthe result that the saturation point of the air is also -raised, and the air is capable of carrying the water vapor from the steam line 51. Thus, the airV saturated at a temperature of about C. enters the compartment 13 of the electrical precipitator and .after absorbing heat from the beforementioned producer-gas in said precipitator at a temperature of about 120 C., the saturated air lemerges from the l:compartment 13 ofthe electrical precipitator at a temperature of about 116 C., and passes to the superheater 9.

In the super-heater 9, the air passes in counter-current with waste gases, preferably from the stack of the coke-ovens '5, which waste gases enter the super-heater at a temi perature ofabout 300- C. The super-heated air emerges from the super-heater 9 with its temperature raised to about 250 C, and passes to the grate of the producer. The Waste gases from the coke-ovens pass through a waste heatjine 53 and fan 52 to the superheater 9; from the super-heater 9 these gases, ar'terY a large proportion. of their waste' heat has been utilized in the super-heating ofthe saturated air, discharge through a v stack line 54 to the stack 55. If desired, the super-heater may take all orpart of the .waste from the ovens. In order to effeet this control, a by-pass 56is introduced Ain the line 53, permitting a proportion of the waste from the coke-ovens to flow to the supereater and another portion to the stack 55. The by-pass 56 may be further regulated so that the entire volume of waste as iront the coke-ovens Hows -to the supereater and is discharged direct] from the super-heater 9 into the stack 55. Y y the employment of the clean stack gases from the coke-ovens, there is eliminated stoppage of the tubes in the super-heater, such as might be occasioned bythe use of the hot dust-charged producer gas. The waste gases ,from the coke-ovens are quite clean and free from dust and hence the tubesin the super-heater last longer and do not have to be cleaned.

The coke-oven gas from the coke-ovens passes through the as line 39, at a'temperature of about 80 to the primary cooler 40, and is thence forwarded b the exhauster 41 -to the compartment 42 o the electrical precipitator, the other before-mentioned compartment 13 of which serves for the pre-'- cipitation of tar from the producer-gas. In the primary cooler 40, the coke-oven gas is cooled, to about 25 C. andthe consequent condensation of tar and ammonia liquor is drained fromsuch cooler and conveyed to the tar andl liquor tank 14, in which the tar andammonia liquor are separated, the tar flowing oil' into the tar tank 11, and the ammonia liquor flowing to the ammonia still 43. The vapors from this still ow at a temperature of about 100 CJ, through the ammonia vapor line 44 leading into the coke! oven gas line between' the exhauster41 and the electrical precipitator compartment 42,

and the mixture of such vapors and-coke-l oven gas enters the saidprecipitator compartment at a temperature of about 35 C. At this temperature, both the tar residue in the coke-oven gas and the water of the still vapors will be precipitated in said precipitator compartment 42, and' the. so precipitated'tar andconden'satelow olf from the precipitator into the before-mentioned tar and liquor tank 14. The tar-freed coke-oven gas with its own content of ammonia and its mlxture of ammonia Avapor from-the still flows. from the electrical precipitatorcompartment. 42 to the `before-mentioned satu# rater 27, entering the same at a temperature of about 35 C., or such temperature may be raised al little by passing the gas through a small reheater 45 around which the gas is 'preerablybypassed on its way from 'the said preclpitator to the said saturater 27. Discharging through the saturation bath 'of fate derived not only fromthe said ammonia of the coke-oven gas, but also from the am monia of the acld solution from the acidv washer 16 for the producer-gas, thus accomplishing a combined vand simultaneous're-A my handfhis rom one saturation bath. The

cold water' from the before-mentioned water tank 32; the finally cooled coke-oven gas at' a temperature of about 25 C., passes from said final cooler to the coke-oven gas-holder 47, and thence to ywhatever service 'itmay be employed in.

The processes of the inventiony may be practised in various ways, other than the v particular embodiment that has .been described for purposes of illustration, and still be within the scopo and subject matter of the claims hereinafter'made.

What is claimed is:

1. In a process for the production of ammonia from producer gas; the combination of steps that consists in: heating watercharged air going to a 'producer Vby passing such air in' heat-exchangingrelation with a hot extraneously-derived gas of regulable temperature; extracting the tar, from the producer gas; and then recovering the ammonia from lthe tar-freed gas, the ammonia production being controlled by the heating of the air by a waste gas of re lable temperature; substantially as speced.

2. In a process forthe recovery of tar and ammonia from producer gas, the combination of steps that consists in: concurrently Y i cooling and preciipritating the dust from the hot producer gas om the producer; further cooling and washing said producer gas with water; then precipitating the residue of the 3. yIn a process for the recoveryA of tar and ammonia from producer gas, the combination of steps that consists 1n: subjecting the hot producer gas from Vthe producer to a water-wash treatment to precipitate the dust stantially the temperature of precipitation of the tar; then precipitating the tar from the partially cooled but still hot gas; and

then passing such gas through an'acid wash 'to absorb the ammonia., substantially'` as speciled.

.tar from such partially cooled but ,still hot gas; and then passing said gas through an .acid wash to absorb the ammonia, substantially as" specied.

-from-said gas and to cool the gasto sub- In testimony whereofl have hereunto set il 15th da of Au t 1919.- JosE H viNiEREN. 

